xUnit assertThat / Matcher

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assertThat / Matcher とは？
サンプルプログラム
Matcher
独自の Matcher

assertThat / Matcher とは？ †

JUnit 4.4 から導入された期待値(expected)、実測値(actual)比較フレームワーク
assertEquals(EXPECTED, ACTUAL) と assertThat(ACTUAL, is(EXPECTED)) は、期待値と実測値が逆

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サンプルプログラム †

テスト対象

package com.mycompany.sandbox;

public class App {

    public static void main(String[] args) {
        App thisObj = new App();
        
        System.out.println(thisObj.factorial(Integer.parseInt(args[0])));
    }

    /**
     * x! を求めます.
     *
     * @param x 数値
     * @return x!
     */
    public int factorial(final int x) {
        return recursive(x);
    }

    /**
     * 再帰的に x * recursive(x-1) を実行します.
     *
     * @param x 数値
     * @return x!
     */
    private int recursive(final int x) {
        if (x == 1) {
            return x;
        }
        return x * recursive(x - 1);
    }
}

テストプログラム

package com.mycompany.sandbox;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import org.junit.Test;

/**
 * Unit test for simple App.
 */
public class AppTest {

    @Test
    public void test() {
        App app = new App();
        assertThat(app.factorial(10), is(3628800));   
    }
}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mycompany</groupId>
    <artifactId>Sandbox</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>Sandbox</name>
    <url>http://maven.apache.org</url>
    
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.0</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-site-plugin</artifactId>
                <version>3.2</version>
                <configuration>
                    <locales>ja</locales>
                    <inputEncoding>UTF-8</inputEncoding>
                    <outputEncoding>UTF-8</outputEncoding>
                    <reportPlugins>
                        <plugin>
                            <groupId>org.jacoco</groupId>
                            <artifactId>jacoco-maven-plugin</artifactId>
                            <version>0.6.0.201210061924</version>
                        </plugin>
                    </reportPlugins>
                </configuration>
            </plugin>            
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.hamcrest</groupId>
            <artifactId>hamcrest-library</artifactId>
            <version>1.3</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

hamcrest-core は、junit 4.11 が依存しているので、勝手にライブラリに入る hamcrest = matchers

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Matcher †

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hamcrest-core †

assertThat(ACTUAL, is(EXPECTED));
assertThat(ACTUAL, is(nullValue()));
assertThat(ACTUAL, is(notNullValue?()));
assertThat(ACTUAL, is(not(EXPECTED)));
assertThat(ACTUAL, is(sameInstance(EXPECTED)));
assertThat(ACTUAL, is(instanceOf(EXPECTED.class)));
assertThat(ACTUAL LIST, hasItem(EXPECTED));
assertThat(ACTUAL LIST, hasItems(EXPECTED1, EXPECTED2));
assertThat(ACTUAL, startsWith(EXPECTED));
assertThat(ACTUAL, endWith(EXPECTED));

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hamcrest-library †

http://www.jarvana.com/jarvana/view/org/hamcrest/hamcrest-library/1.2/hamcrest-library-1.2-javadoc.jar!/index.html
https://code.google.com/p/hamcrest/wiki/Tutorial
beans : Bean
collections : List
number : 範囲や大小
object : class や ATW のイベントなど
text : ある文字を除外指定の比較など
xml : XPath の存在チェックなど

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import static org.junit.matchers.JUnitMatchers?.* †

JUnit 標準の Matcher だが、4.11 では、軒並み非推奨になっている

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独自の Matcher †

引数の倍数であるかを確かめる Matcher

package com.mycompany.sandbox;

import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;

public class IsMultiple extends BaseMatcher<Integer> {

    private int expectNum;
    private int actualNum;
    
    public static IsMultiple multipleOf(int num) {
        return new IsMultiple(num);
    }
    
    public IsMultiple(int num) {
        expectNum = num;
    }
    
    @Override
    public boolean matches(Object actual) {
        if (actual == null || !(actual instanceof Integer)) {
            return false;
        }
        actualNum = ((Integer) actual).intValue();
        
        return (actualNum % expectNum == 0);
    }

    @Override
    public void describeTo(Description desc) {
        desc.appendText(" multiple of ");
        desc.appendValue(expectNum);
    }
}

BaseMatcher? を継承
matcher(Obj) で検証する
describeTo(Desc) でエラーメッセージを構築する
そのほかに、public static な factory メソッドを作る

使い方

package com.mycompany.sandbox;

import static com.mycompany.sandbox.IsMultiple.multipleOf;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import org.junit.Test;

public class AppTest {

    @Test
    public void test() {
        assertThat(100, is(multipleOf(3)));   
    }
}

is() は、引数の matcher を実行するだけなので無くても良いけど、分かりやすくするために入れとく

実行結果

Java#xUNIT